Methods and apparatus for operating mobile nodes in multiple states

ABSTRACT

The use of multiple states of mobile communication device operation to allow a single base station to support a relatively large number of mobile nodes is described. The various states require different amounts of communications resources, e.g., bandwidth. Four supported states of operation are a on-state, a hold-state, a sleep-state, and an access-state. Each mobile node in the on-state is allocated communication resources to perform transmission power control signaling, transmission timing control signaling and to transmit data as part of a data uplink communications operation. Each mobile node in the hold-state is allocated communication resources to perform transmission timing control signaling and is provided a dedicated uplink for requesting a state transition and a shared resource for transmitting acknowledgements. In the sleep state a mobile node is allocated minimal resources and does not conduct power control signaling or timing control signaling. Data may be received in the on and hold states.

RELATED APPLICATION

[0001] This application claims the benefit of U.S. Provisional PatentApplication S. No. 60/401,520 filed on Aug. 8, 2002, titled: “Methodsand Apparatus for Implementing Mobile Communications System” which ishereby expressly incorporated by reference.

FIELD OF THE INVENTION

[0002] The present invention is directed to wireless communicationssystems and, more particularly, to methods and apparatus for supportinga plurality of mobile nodes in a communications cell with limitedresources.

BACKGROUND OF THE INVENTION

[0003] Wireless communications systems are frequently implemented as oneor more communications cells. Each cell normally includes a base stationwhich supports communications with mobile nodes that are located in, orenter, the communications range of the cell's base station. Within acell or a sector of a cell, the unit of communications resource is asymbol, e.g., QPSK or QAM transmitted on one frequency tone for one timeslot in an orthogonal frequency division multiplexed (OFDM) system. Thetotal available communication resource is divided into a number of suchsymbols (units) which can be used for communicating control and datainformation between a base station and one or more mobile nodes in thecell and tends to be limited. Control signals transmitted between a basestation and a mobile node may be transmitted in two possible directions,i.e., from the base station to the mobile node or from the mobile nodeto the base station. Transmission of signals from the base station tothe mobile is often called a downlink. In contrast, transmission fromthe mobile to the base station is commonly referred to as an uplink.

[0004] In order to provide efficient use of limited communicationsresources, base stations may allocate different numbers of tones todifferent mobile nodes depending on the devices' bandwidth needs. In amultiple access system, several nodes may be transmitting data, e.g., inthe form of symbols, to a base station at the same time using differenttones. This is common in OFDM systems. In such systems, it is importantthat symbols from different mobile nodes arrive at the base station in asynchronized manner, e.g., so the base station can properly determinethe symbol period to which a received symbol belongs and signals fromdifferent mobile nodes do not interfere with each other. As mobile nodesmove in a cell, transmission delay will vary as a function of thedistance between a mobile node and a base station. In order to make surethat transmitted symbols will arrive at a base station from differentmobile nodes in synchronized manner, timing control signals, e.g.,feedback signals, may be and in many cases are, transmitted to eachactive mobile node of a cellular system. The timing control signals areoften specific to each device and represent, e.g., timing corrections ofoffsets to be used by the device to determine symbol transmissiontiming. Timing control signaling operations include, e.g., monitoringfor timing control signals, decoding received timing control signals,and performing timing control update operations in response to thedecoded received timing control signals.

[0005] Timing control signals can be particularly important in systemswhere there are a large number of mobile nodes. In order to avoidinterference from a mobile node due to timing miss synchronization, itmay be necessary to establish timing synchronization and control beforeallowing a mobile node to transmit data, e.g., voice data, IP packetsincluding data, etc. to a base station.

[0006] In addition to managing limited resources such as bandwidth,power management is often a concern in wireless communications systems.Mobile nodes, e.g., wireless terminals, are often powered by batteries.Since battery power is limited, it is desirable to reduce powerrequirements and thereby increase the amount of time a mobile node canoperate without a battery recharge or battery replacement. In order tominimize power consumption, it is desirable to limit the amount of powerused to transmit signals to a base station to the minimal amount ofpower required. Another advantage of minimizing mobile node transmissionpower is that it has the additional benefit of limiting the amount ofinterference that the transmissions will cause in neighboring cellswhich will often use the same frequencies as an adjoining cell.

[0007] In order to facilitate transmission power control, power controlsignaling, e.g., a feedback loop, may be established between a basestation and a mobile node. Power control signaling often takes place ata much faster rate than the timing control signaling. This is becausepower control signaling attempts to track variations in the signalstrength between the base station and the mobile nodes and this cantypically vary on the scale of milliseconds. The timing control needs totake into consideration changes in the distance between base station andthe mobile nodes and this tends to vary on a much slower scale,typically hundreds of milliseconds to seconds. Thus the amount ofcontrol signaling overhead for power control tends to be much more thanthat for timing control.

[0008] In addition to timing and power control signaling, other types ofsignaling may be employed. For example mobile nodes in addition may alsosignal on an uplink the quality of the downlink channel. This may beused by the base station to determine the communication resourceallocation to allow for the transfer of data packets from the basestation to the mobile. Such downlink channel quality reports allows abase station to determine which mobile node to transmit to and if amobile node is chosen then the amount of forward error correctionprotection to apply to the data. These downlink channel quality reportsgenerally are signaled on a similar time scale as the power controlsignaling. As another example, signaling may be used to periodicallyannounce a mobile node's presence in a cell to a base station. It canalso be used to request allocation of uplink resources, e.g., totransmit user data in a communications session. Shared as opposed todedicated resources may be used for such announcements and/or resourcerequests.

[0009] Signaling resources, e.g., time slots or tones, may be shared ordedicated. In the case of shared time slots or tones, multiple devicesmay attempt to use the resource, e.g., segment or time slot, tocommunicate information at the same time. In the case of a sharedresource, each ode in the system normally tries to use the resource onan as needed basis. This sometimes results in collisions. In the case ofdedicated resources, e.g., with time slots and/or tones being allocatedto particular communications device or group of devices to the exclusionof other devices for a certain period of time, the problem of possiblecollisions is avoided or reduced. The dedicated resources may be part ofa common resource, e.g., a common channel, where segments of the channelare dedicated, e.g., allocated, to individual devices or groups ofdevices where the groups include fewer than the total number of mobilenodes in a cell. For example, in the case of an uplink time segments maybe dedicated to individual mobile nodes to prevent the possibility ofcollisions. In the case of a downlink, time slots may be dedicated toindividual devices or, in the case of multicast messages or controlsignals, to a group of devices which are to receive the same messagesand/or control signals. While segments of a common channel may bededicated to individual nodes at different times, over time multiplenodes will use different segments of the channel thereby making theoverall channel common to multiple nodes.

[0010] A logical control channel dedicated to an individual mobile nodemay be comprised of segments of a common channel dedicated for use bythe individual mobile node.

[0011] Dedicated resources that go unused may be wasteful. However,shared uplink resources which may be accessed by multiple userssimultaneously may suffer from a large number of collisions leading towasted bandwidth and resulting in an unpredictable amount of timerequired to communicate.

[0012] While timing and power control signals and downlink channelquality reports are useful in managing communications in a wirelesscommunications system, due to limited resources it may not be possiblefor a base station to support a large number of nodes when powercontrol, and other types of signaling need to be supported on acontinuous basis for each node in the system.

[0013] In view of the above discussion, it is apparent that there is aneed for improved methods of allocating limited resources to mobilenodes to permit a relatively large number of nodes to be supported by asingle base station with limited communications resources. It isdesirable that at least some methods of communications resourceallocation and mobile node management take into consideration the needfor timing control signaling and the desirability of power controlsignaling in mobile communications systems.

SUMMARY OF THE INVENTION

[0014] The present invention is directed to methods and apparatus forsupporting multiple wireless terminals, e.g., mobile nodes, using asingle base station and limited resources such as bandwidth for thetransmission of signals between the base station and mobile nodes, e.g.,in a communications cell. A system may be implemented in accordance withthe invention as a plurality of cells, each cell including at least onebase station which serves multiple mobile nodes. A mobile node can, butneed not, move within a cell or between cells.

[0015] In accordance with the present invention, mobile nodes supportmultiple states of operation. The control signaling resources used by amobile node vary depending on the state of operation. Thus, depending onthe state of the mobile node, a large amount of signaling resources maybe required while in other states a minimum amount of resources may berequired. Control signaling resources are in addition to datatransmission resources, e.g., bandwidth used to communicate payload datasuch as voice, data files, etc. By supporting different mobile nodestates of operation, requiring differing amounts of base station/mobilenode control communications resources, e.g., signal bandwidth, used forcontrol purposes, more mobile nodes can be supported by a base stationthan could be supported if all mobile nodes were allocated the sameamount of communications resources for control signaling purposes.

[0016] Bandwidth allocated to a particular mobile device forcommunicating control signals between the mobile device and a basestation is known as dedicated control bandwidth. Dedicated controlbandwidth may comprise multiple dedicated logical or physical controlchannels. In some embodiments, each dedicated control channelcorresponds to one or more dedicated segments of a common controlchannel. Control channel segments may be, e.g., channel time slots usedfor transmitting and/or receiving control signals. Dedicated uplinkcontrol channel segments differ from shared uplink control channelsegments where multiple devices share the same bandwidth for uplinksignaling.

[0017] In the case of a shared communications channel conflicts mayresult when multiple nodes, at the same time attempt to transmit acontrol signal using the shared communications channel.

[0018] Mobile nodes implemented in accordance with one exemplaryembodiment support four states, e.g. modes of operation. The four statesare a sleep state, a hold state, an access state, and an on state. Ofthese the access state is a transitory stage and the other states aresteady states and the mobile nodes can be in these states for anextended period of time.

[0019] Of the four states, the on state requires the highest amount ofcontrol signaling resources, e.g., bandwidth used for control signalingpurposes. In this state, the mobile node is allocated bandwidth on asneeded basis for transmitting and receiving traffic data, e.g., payloadinformation such as text or video. Thus, at any given time in the onstate a mobile node may be allocated a dedicated data channel fortransmitting payload information. In the on state the mobile node isalso allocated a dedicated uplink control signaling channel.

[0020] In various embodiments, a dedicated uplink control channel isused during the on state by the MN to make downlink channel qualityreports, communicate resource requests, implement session signaling,etc. Downlink channel quality reports are normally signaled frequentlyenough to track variations in the signal strength between the basestation and the mobile node.

[0021] During the on state, the base station and mobile node exchangetiming control signals using one or more dedicated control channelsallowing the mobile node to periodically adjust its transmission timing,e.g., symbol timing, to take into consideration changes in distance andother factors which might cause the transmitted signals to drift timingfrom the base station's perspective, with the signals transmitted byother mobile nodes. As discussed above, the use of timing controlsignaling and performing timing control signaling operations, such asupdating transmission timing, is important in many systems which useorthogonal frequency division multiple access in the uplink to avoidinterference from transmission signals generated by multiple nodes inthe same cell.

[0022] To provide transmission power control, during the on state,transmission power control signaling is employed to provide a feedbackmechanism whereby a mobile node is able to efficiently control itstransmission power levels based on signals periodically received fromthe base station with which it is communicating. In various embodimentsthe base station periodically transmits power control signals over adedicated control downlink. As part of the transmission power controlsignaling process, the mobile node, performs various transmission powercontrol signaling operations including, for example, monitoring fortransmission power control signals directed to the particular mobilenode, decoding received transmission power control signals, and updatingits transmission power levels based on the received and decodedtransmission power control signals. Thus, in response to receiving powercontrol signals in a dedicated downlink segment corresponding to theparticular mobile node, the mobile node adjusts its transmission powerlevel in response to the received signal. In this manner, a mobile nodecan increase or decease its transmission power to provide for successfulreceipt of signals by the base station without excessive wastage ofpower and therefore reducing interference and improving battery life.The power control signaling is typically carried out sufficientlyfrequently to track fast variations in the signal strength between thebase station and the mobile nodes. The power control interval is afunction of smallest channel coherence time that the system is designedfor. The power control signaling and the downlink channel qualityreports are normally of similar time scale, and in general, occur at amuch higher frequency than the timing control signaling. However, inaccordance with one feature of the present invention the base stationvaries the rate at which it transmits power control signals to a mobilenode as a function of the mobile node's state of operation. As a result,in such an embodiment, the rate at which the mobile node performstransmission power control adjustments will vary as a function of thestate in which the mobile node operates. In one exemplary embodiment,power control updates are not performed in the sleep state and, whenperformed in the hold state, are normally performed at a lower rate thanduring the on state.

[0023] Operation of a mobile node in the hold state requires fewercontrol communications resources, e.g., bandwidth, than are required tosupport operation of a mobile node in the on state. In addition, invarious embodiments while in the hold state a mobile node is deniedbandwidth for transmitting payload data, but the mobile can be allocatedbandwidth for receiving payload data. In such embodiments the mobilenode is denied a dedicated data uplink communications channel during thehold state. The bandwidth allocated for receiving data may be, e.g., adata downlink channel shared with other mobile nodes. During the holdstate timing control signaling is maintained and the mobile node is alsoallocated a dedicated control uplink communication resource, e.g.,dedicated uplink control communications channel, which it can use torequest changes to other states. This allows, for example, a mobile nodeto obtain additional communications resources by requesting a transitionto the on state where it could transmit payload data. In some but notall embodiments, in the hold state, the dedicated uplink control channelis limited to the communication of signals requesting permission tochange the state of mobile node operation, e.g., from the hold state tothe on state. During the hold state the bandwidth allocated, e.g.,dedicated, to a mobile node for control signaling purposes is less thanin the on-state.

[0024] Maintaining timing control while in the hold-state allows themobile nodes to transmit their uplink requests without generatinginterference to other mobiles within the same cell and having adedicated uplink control resource ensures that the delays for statetransition are minimal as the requests for state transitions do notcollide with similar requests from other mobile nodes as may occur inthe case of shared uplink resources. Since timing control signaling ismaintained, when the mobile node transitions from the hold state to theon state it can transmit data without much delay, e.g., as soon as therequested uplink resource is granted, without concerns about creatinginterference for other mobile nodes in the cell due to drift of uplinksymbol timing. During the hold state, transmission power controlsignaling may be discontinued or performed less frequently, e.g., atgreater intervals than performed during on state operation. In thismanner, the dedicated control resources used for power control signalingcan be eliminated or reduced allowing fewer resources to be dedicated tothis purpose than would be possible if power control signaling for allnodes in the hold state was performed at the same rate as in the onstate.

[0025] When transitioning from the hold state to the on state, themobile node may start off with an initial high power level to insurethat its signals are received by the base station with the power levelbeing reduced once transmission power control signaling resumes at anormal rate as part of on state operation. In one exemplary embodiment,when the mobile node in the hold state intends to migrate to the onstate, it transmits a state transition request using a dedicated uplinkcommunication resource, which is not shared with any other mobile nodes.The base station then responds with a broadcast message indicating itsresponse to the mobile's state transition request. The mobile onreceiving the base station message meant for it responds with anacknowledgement. The acknowledgment is transmitted over a sharedresource on the uplink and is slaved to the broadcast message on thedownlink.

[0026] By transmitting an appropriate state transition request themobile may also transition to the sleep state. In one exemplaryembodiment, when the mobile node does not intend to migrate to anotherstate, the mobile node may not transmit any signal in its dedicateduplink communication channel, though the dedicated channel has beenassigned to the mobile node and is therefore not used by any othermobile nodes. In another embodiment, the mobile node uses an on/offsignaling in its dedicated uplink communication channel, where themobile node sends a fixed signal (on) when it intends to migrate toanother state and does not send any signal (off) when it does not intendto migrate to any other state. In this case, the transmission of thefixed signal can be interpreted as a migration request to the on stateif the transmission occurs at certain time instances, and as a migrationrequest to the sleep state if the transmission occurs at some other timeinstances.

[0027] In order to support a large number of mobile nodes, a sleep staterequiring relatively few communications resources is also supported. Inan exemplary embodiment, during the sleep state, timing control signaland power control signaling are not supported.

[0028] Thus, in the sleep state, the mobile nodes normally do notperforming transmission timing control or transmission power controlsignaling operations such as receiving, decoding and using timing andtransmission power control signals. In addition, the mobile node is notallocated a dedicated uplink control resource, e.g., uplink controlcommunications channel, for making state transition requests or payloadtransmission requests. In addition, during the sleep state the mobilenode is not allocated data transmission resources, e.g., dedicatedbandwidth, for use in transmitting payload data, e.g., as part of acommunications session with another node conducted through the basestation.

[0029] Given the absence of a dedicated uplink control channel duringthe sleep state, a shared communications channel is used to contact thebase station to request resources necessary for a mobile node toinitiate transition from the sleep state to another state.

[0030] In some embodiments, in the sleep state the mobile node may, atthe behest of the base station serving the cell, signal its presence inthe cell, e.g., using a shared communications resource. However, asdiscussed above, little other signaling is supported during this stateof operation. Thus, very little control signaling bandwidth is used tocommunicate control information between mobile nodes in the sleep stateand a base station serving the nodes.

[0031] The access state is a state through which a node in the sleepstate can transition into one of the other supported states. Thetransition between states may be triggered by an action by a user of themobile node, e.g., an attempt to transmit data to another mobile node.Upon entering the access state, transmission power control and timingcontrol signaling has not yet been established. During access stateoperation, timing control signaling is established and, in variousembodiments, full or partial transmission power control signaling isestablished. A mobile node can transition from the access state toeither the on state or the hold state.

[0032] The establishment of the timing synchronization and transmissionpower control can take some amount of time during which data transitionis delayed. Also the access process happens through a shared media andcontentions between mobile nodes need to be resolved. By supporting ahold state in accordance with the present invention, in addition to asleep state, such delays can be avoided for a number of mobile nodes, astransition from the hold state to the on state does not go through theaccess state, while the number of nodes which can be supported by asingle base station is larger than would be possible without the use ofreduced signaling states of mobile node operation.

[0033] In some embodiments, for an individual cell, the maximum numberof mobile nodes that can be in the sleep state at any given time is setto be greater than the maximum number of mobile nodes that can be in thehold state at given time. In addition, the maximum number of mobilenodes which can be in the hold at any given time is set to be greaterthan the maximum number of nodes that can be in the on state at anygiven time.

[0034] In accordance with a power conservation feature of the presentinvention, downlink control signaling from the base station to themobile nodes is divided into a plurality of control channels. Adifferent number of downlink control channels are monitored by a mobilenode depending on the node's state of operation. During the on state thegreatest number of downlink control channels are monitored. During thehold state a smaller number of downlink control channels are monitoredthan during the on state. In the sleep state the smallest number ofdownlink control channels are monitored.

[0035] To further reduce power consumption in the mobile node associatedwith monitoring for control signals, in accordance with one feature ofthe invention control channels monitored during the hold and sleepstates are implemented as periodic control channels. That is, signalsare not broadcast on a continuous basis on the control channelsmonitored in the hold and sleep states. Thus, during the hold and sleepstates the mobiles monitor for control signals at periodic intervals andsave power by not monitoring for control signals at those times whencontrol signals are not transmitted on the monitored channels. Tofurther decrease the time a particular mobile needs to monitor forcontrol signals during the hold and sleep states, portions, e.g.,segments, of the periodic control channels may be dedicated to one or agroup of mobile nodes. The mobile nodes are made aware of which controlchannel segments are dedicated to them and then monitor the dedicatedsegments as opposed to all the segments in the control channels. Thisallows monitoring for control signals to be performed in the hold andsleep states by individual mobile nodes at greater periodic intervalsthan would be possible if the mobile were required to monitor allsegments of the periodic control channels.

[0036] In one particular embodiment, during the on state, mobile nodesmonitor segments of an assignment channel on a continuous basis and alsomonitor segments of periodic fast paging and slow paging controlchannels. When in the hold state the mobiles monitor the fast paging andslow paging control channels. Such monitoring may involve monitoring asubset of the segments of the periodic fast and slow paging channels,e.g., segments dedicated to the particular mobile node. During the holdstate in the particular exemplary embodiment the slow paging channel ismonitored but not the fast paging channel or the assignment channel.

[0037] The paging control channels may be used to instruct the mobilenode to change states. By limiting the number of control channels andthe rate of control channel monitoring as a function of the state ofoperation, power resources can be conserved in accordance with theinvention while operating in the hold and sleep states.

[0038] Numerous additional features, benefits and details of the methodsand apparatus of the present invention are described in the detaileddescription which follows.

BRIEF DESCRIPTION OF THE DRAWINGS

[0039]FIG. 1 illustrates an exemplary communication cell, which may bepart of a communications system, implemented in accordance with thepresent invention.

[0040]FIG. 2 illustrates a base station implemented in accordance withthe present invention.

[0041]FIG. 3 illustrates a mobile node implemented in accordance withthe present invention.

[0042]FIG. 4 is a state diagram illustrating the different states that amobile node may enter while operating in accordance with the presentinvention.

[0043]FIG. 5 is a chart illustrating various control and signalingmodules that are executed by a mobile node during each of the differentstates illustrated in FIG. 4.

[0044]FIG. 6 illustrates the transmissions associated with threeexemplary downlink control channels used in accordance with oneembodiment of the present invention.

[0045]FIG. 7 illustrates which control channels shown in FIG. 6 aremonitored in each of the four states in which a mobile node of thepresent invention may operate.

DETAILED DESCRIPTION

[0046]FIG. 1 illustrates a communications cell 10 implemented inaccordance with the present invention. A communications system mayinclude multiple cells of the type illustrated in FIG. 1. Thecommunications cell 10 includes a base station 12 and a plurality, e.g.,a number N, of mobile nodes 14, 16 which exchange data and signals withthe base station 12 over the air as represented by arrows 13, 15. Inaccordance with the invention, the base station 12 and mobile nodes 14,16 are capable of performing and/or maintaining control signalingindependently of data signaling, e.g., voice or other payloadinformation, being communicated. Examples of control signaling includepower control, downlink channel quality reports, and timing controlsignaling.

[0047]FIG. 2 illustrates a base station implemented in accordance withthe present invention. As shown, the exemplary BS 12 includes a receivercircuit 202, transmitter circuit 204, processor 206, memory 210 and anetwork interface 208 coupled together by a bus 207. The receivercircuit 202 is coupled to an antenna 203 for receiving signals frommobile nodes.

[0048] The transmitter circuit 204 is coupled to a transmitter antenna205 which can be used to broadcast signals to mobile nodes. The networkinterface 208 is used to couple the base station 12 to one or morenetwork elements, e.g., routers and/or the Internet. In this manner, thebase station 12 can serve as a communications element between mobilenodes serviced by the base station 12 and other network elements.

[0049] Operation of the base station 12 is controlled by the processor206 under direction of one or more routines stored in the memory 210.Memory 210 includes communications routines 223, data 220, sessionmanagement/resource allocation routine 222, session and resourcesignaling subroutine 224, and active user information 212.Communications routines 223, include various communications applicationswhich may be used to provide particular services, e.g., IP telephonyservices or interactive gaming, to one or more mobile node users. Data220 includes data to be transmitted to, or received from, one or moremobile nodes. Data 220 may include, e.g., voice data, E-mail messages,video images, game data, etc.

[0050] The session management and resource allocation routine 222operates in conjunction with subroutines 224 and active user information212 and data 220. The routine 222 is responsible for determining whetherand when mobile nodes may transition between states and also theresources allocated to a mobile node within a state. It may base itsdecision on various criteria such as, requests from mobile nodesrequesting to transition between states, idletime/time spent by a mobilein a particular state, available resources, available data, mobilepriorities etc. These criteria would allow a base station to supportdifferent quality of service (QOS) across the mobile nodes connected toit.

[0051] The session and resource signaling subroutine 224 is called bysession management routine 222 when signaling operations are required.Such signaling is used to indicate the permission to transition betweenstates. It is also used to allocate the resources, e.g., when in aparticular state. For example, in the on state a mobile node may begranted resources to transmit or receive data.

[0052] Active user information 212 includes information for each activeuser and/or mobile node serviced by the base station 12. For each mobilenode and/or user it includes a set of state information 213, 213′. Thestate information 213, 213′ includes, e.g., whether the mobile node isin an on state, a hold state, a sleep state, or an access state assupported in accordance with the present invention, number and types ofdata packets currently available for transmission to or from the mobilenode, and information on the communication resources used by the mobilenode.

[0053]FIG. 3 illustrates an exemplary mobile node 14 implemented inaccordance with the invention. The mobile node 14 includes a receiver302, a transmitter 304, antennas 303, 305, a memory 210 and a processorcoupled together as shown in FIG. 3. The mobile node uses itstransmitter 306, receiver 302, and antennas 303, 305 to send and receiveinformation to and from base station 12.

[0054] Memory 210 includes user/device information 312, data 320, apower control and power control signaling module 322, a timing controland timing control signaling module 324, a device status control andstatus signaling module 326, and a data control and data signalingmodule 328. The mobile node 14 operates under control of the modules,which are executed by the processor 306. User/device information 312includes device information, e.g., a device identifier, a networkaddress or a telephone number. This information can be used, by the basestation 12, to identify the mobile nodes, e.g., when assigningcommunications channels. The user/device information 312 also includesinformation concerning the present state of the mobile device 14. Thedata 320 includes, e.g., voice, text and/or other data received from, orto be transmitted to, the base station as part of a communicationssession.

[0055] Device status control and status signaling module 326 is used fordevice status control and status signaling. Device status control module326 determines, in conjunction with signals received from the basestation 12, what mode, e.g., state, the mobile node 14 is to operate inat any given time. In response to, e.g., user input, the mobile node 14may request permission from the base station 12 to transition from onestate to another and to be granted the resources associated with a givenstate. Depending on the state of operation at any given time and thecommunications resources allocated to the mobile node 14, status controland status signaling module 326 determines what signaling is to occurand which signaling modules are to be active. In response to periods ofreduced signal activity, e.g., control signal activity, status controland status signaling module 326 may decide to transition from a currentstate of operation to a state of operation requiring fewer controlresources and/or requires less power. The module 326 may, but need not,signal the state transition to the base station. Status control andstatus signaling module 326 controls, among other things, the number ofdownlink control channels monitored during each state of operation and,in various embodiments, the rate at which one or more downlink controlchannels are monitored.

[0056] As part of the processes of controlling the state of the mobilenode 14, and overseeing general signaling between the mobile node 14 andbase station 12, the signaling module is responsible for signaling tothe base station 12, when the mobile node 14 first enters a cell and/orwhen the base station 12 requests that the mobile node 14 indicate itpresence. The mobile node 14 may use a shared communication resource tosignal its presence to the cell's base station 12, while a dedicatedcommunication resource may be used for other communication signals,e.g., uploading and downloading data files as part of a communicationsession.

[0057] Transmission power control and power control signaling module 322is used to control the generation, processing and reception oftransmission power control signals. Module 322 controls the signalingused to implement transmission power control through interaction withthe base station 12. Signals transmitted to, or received from the basestation 12 are used to control mobile node transmission power levelsunder direction of module 322. Power control is used by the base station12 and the mobile nodes 14, 16 to regulate power output whentransmitting signals. The base station 12 transmits signals to themobile nodes which are used by the mobile nodes in adjusting theirtransmission power output. The optimal level of power used to transmitsignals varies with several factors including transmission burst rate,channel conditions and distance from the base station 12, e.g., thecloser the mobile node 14 is to the base station 12, the less power themobile node 14 needs to use to transmit signals to the base station 12.Using a maximum power output for all transmissions has disadvantages,e.g., the mobile node 14 battery life is reduced, and high power outputincreases the potential of the transmitted signals causing interference,e.g., with transmissions in neighboring or overlapping cells.Transmission power control signaling allows the mobile node to reduceand/or minimize transmission output power and thereby extend batterylife.

[0058] Timing control and timing control signaling module 324 is usedfor timing and timing signaling. Timing control is used in wirelessnetworking schemes such as, e.g., those with uplinks based on orthogonalfrequency division multiple access. To reduce the effects of noise, tonehopping may also be used. Tone hopping may be a function of time withdifferent mobile nodes being allocated different tones during differentsymbol transmission time periods, referred to as symbol times. In orderfor a base station 12 of a multiple access system to keep track of, anddistinguish between, signals from different mobile nodes, it isdesirable for the base station 12 to receive information from the mobilenodes in a synchronized manner. A drift of timing between the mobilenode 14 and the base station 12 can cause transmission interferencemaking it difficult for the base station to distinguish between symbolstransmitted by different mobile nodes, e.g., using the same tone, butduring different symbol time periods or using different tones but duringthe same symbol time period.

[0059] For example, the effect on a mobile node's distance from the basestation is a factor since transmissions from mobile node that arefarther from the base station 12 take longer to reach the base station12. A late arriving signal can interfere with another connection thathas hopped to the late arriving signal's frequency in a latter timeperiod. In order to maintain symbol timing synchronization, it isrequired to instruct a node to advance or delay its symbol transmissionstart time to take into consideration changes in signal propagation timeto the base station.

[0060] Data and data signaling module 328 is used to controltransmission and the reception of payload data, e.g., a channel or timeslot dedicated to the mobile node for signaling purposes. This includes,e.g., the data packets of an Internet file transfer operation.

[0061] In accordance with the present invention, the mobile node 14 canbe in one of four states. The signaling, power, and communicationsresources required by a mobile node will vary depending on the sate inwhich the mobile node is operating. As a result of using multiple statesin the mobile nodes, the base station 12 is able to allocate differentdegrees of communication resource, e.g., control and data signalingresource, to different mobile nodes as a function of the node's state ofoperation. This allows the base station 12 to support a greater numberof mobile nodes than would be possible if all nodes were continuously inthe on state. The particular state that the mobile node 14 is indetermines the control signaling and data signaling modules that areexecuted at any given time and also the level of control signalingbetween the mobile node and base station 12. The mobile node 14 can alsotake advantage of the different activity level in different states tosave power and extend battery life.

[0062] Operation of the mobile nodes 14 in different states, inaccordance with the present invention, will now be explained withreference to FIGS. 4 and 5. FIG. 4 illustrates a state diagram 400including four possible states, an access state 402, a on state 404, ahold state 410 and a sleep state 408, that a mobile node 14 can enter.Arrows are used in FIG. 4 to illustrate the possible transitions betweenthe four states.

[0063]FIG. 5 illustrates the mobile node modules 322, 324, 326, 328 thatare in the various states shown in FIG. 4. Each row of the chart 500corresponds to a different state. The first through fourth rows 502,504, 506, 508 correspond to the sleep state, access state, on state, andhold state, respectively. Each column of the chart 500 corresponds to adifferent module within the mobile node 14. For example, the firstcolumn 510 corresponds to the transmission power control and powercontrol signaling module 322, the second column 512 corresponds to thetiming control and timing control signaling module 324, the third column514 corresponds to the device status control and status signaling module326, while the last column 516 corresponds to the data and datasignaling module 328. In FIG. 5, solid lines are used to indicatemodules which are active in a particular state. Short dashed lines areused to indicate modules which may transition from an inactive orreduced activity level to a fully active status before the access stateis exited, assuming the modules are not already fully active. Longdashed lines are used to indicate a module which may be active in astate but which may perform signaling at a reduced rate while in theindicated state as opposed to the signaling rate implemented in the onstate.

[0064] From FIG. 5 it can be seen that during the sleep state the devicestatus control and status signaling module 326 remains active but theother modules are inactive allowing for power conservation and asignificantly restricting mobile node activity. In the access state 402,which serves as transition state, transmission power control and powercontrol signaling module 322, timing control and timing controlsignaling module 324 will become fully active (or active at a reducedrate in the case of the transmission power control and power controlsignaling module 322 in some embodiments) prior to leaving the accessstate 402 to enter the on-state 404 or hold state 410. In the on-state,all signaling modules 322, 324, 326, 328 are fully active requiring themost power from the mobile node's perspective and the highest allocationof communication resources, e.g., bandwidth, from the base station'sperspective. In the hold state, transmission power control and powercontrol signaling module 322 may be inactive or active at a much reducedsignaling rate. Timing control and timing control signaling module 324remains alive as does the device status control and status signalingmodule 326. The data and data signaling module 326 is either inactive oroperates to implement reduced functionality, e.g., receive data but nottransmit data as part of a communication session between various nodes.In this manner, the hold state allows bandwidth and other communicationsresources to be conserved while, in some cases, allowing the mobile nodeto receive, e.g., multi-cast signals and/or messages.

[0065] Each of the states, and potential transition between states, willnow be described in detail with reference to the state diagram of FIG.4.

[0066] Of the four states 402, 404, 410, 408, the on state 404 allowsthe mobile node to perform the widest range of supported communicationsactivities but requires the highest amount of signaling resources, e.g.,bandwidth. In this state 404, which may be thought of as a “fully-on”state, the mobile node 14 is allocated bandwidth on an as needed basisfor transmitting and receiving data, e.g., payload information such astext or video. The mobile node 14 is also allocated a dedicated uplinksignaling channel which it can use to make downlink channel qualityreports, communication resource requests, implement session signaling,etc. To be useful, these downlink channel quality reports should besignaled sufficiently frequently to track variations in the signalstrengths received by the mobile nodes.

[0067] During the on state 404, under control of module 324, the basestation 12 and mobile node 14 exchange timing control signals. Thisallows the mobile node 14 to periodically adjust its transmissiontiming, e.g., symbol timing, to take into consideration changes indistance and other factors which might cause the mobile node transmittedsignals to drift timing at the base station's receiver, with respect tothe signals transmitted by other mobile nodes 16. As discussed above,the use of symbol timing control signaling is employed in many systemswhich use orthogonal frequency division multiple access in the uplink,to avoid interference from transmission signals generated by multiplenodes in the same cell 10.

[0068] To provide transmission power control, during the on state 404,transmission power control signaling is employed, under direction ofmodule 322, to provide a feedback mechanism whereby a mobile node isable to efficiently control its transmission power levels based onsignals periodically received from the base station with which it iscommunicating. In this manner, a mobile node 14 can increase and/ordecrease its transmission power to provide for successful receipt ofsignals by the base station 12 without excessive wastage of power andtherefore reduced battery life. The power control signaling is carriedout sufficiently frequently to track variations in the signal strengthbetween the base station 12 and the mobile nodes 14, 16 for a certainminimum channel coherence time. The power control interval is a functionof channel coherence time. The power control signaling and the downlinkchannel quality reports are of similar time scale, and in general, occurat much higher rate than the timing control signaling required tosupport vehicular mobility.

[0069] From the on state 404, the mobile node 14 can transition intoeither the sleep state 408 or the hold state 410. Each of these statesrequires reduced communication resources, e.g., bandwidth, to supportthan does the on state 404. The transition may be in response to userinput, e.g., a user terminating a communications session or in responseto the loss of communications resources, e.g., bandwidth required tosupport the transmission and/or receipt of information to becommunicated such as voice or data information.

[0070] In accordance with the present invention, in the hold state, amobile node is denied bandwidth for transmitting payload data. However,timing control signaling is maintained and the mobile node is alsoallocated a dedicated uplink communication resource which it can use torequest changes to other states. This allows for instance a mobile nodeto obtain additional communications resources by requesting a transitionto on state where it could transmit payload data. Maintaining timingcontrol during the hold state 410 allows the mobile node 14 to transmitits uplink requests without generating interference to other mobiles 16within the same cell 10. Having a dedicated resource for transmittingrequests to the base station 12 also helps ensure that the delays forstate transition are minimal as these requests do not collide withsimilar requests from other mobiles.

[0071] From the hold state 410, the mobile node may transition into theon state 404, e.g., upon being granted a requested communicationresource. Alternatively, the mobile node can transition into the sleepstate 408. Since timing control signaling is maintained in the holdstate 410, when the mobile node transitions to the on state it cantransmit data without much delay, e.g., as soon as the requestedbandwidth is granted, without concerns about creating interference tothe uplink transmission of other mobile nodes in the cell which couldresult from a timing drift of the mobile node.

[0072] During the hold state 410, transmission power control signalingmay be discontinued or performed at greater intervals, e.g., at asimilar rate as timing control. In this manner, the resource, e.g., basestation to mobile node control resource, used for transmission powercontrol signaling can be eliminated or less resource can be dedicated tothis purpose than would be possible if power control signaling for allnodes 14, 16 in the hold state was performed at the same rate as in theon state. The mobile nodes 14, 16 transmission power control updates areperformed in the mobile node during the hold state at a reduced rate ornot at all, in a manner which corresponds to the reduced transmissionpower control signaling. When transitioning from the hold state 410 tothe on state 404, the mobile node 14 may start off with an initial highpower level to insure that its signals are received by the base station12. The power level is then reduced once transmission power controlsignaling resumes at a normal (full) rate as part of on state operation.

[0073] Transition from hold state can be initiated by base station or bythe mobile nodes. The base station may initiate a transition by sendinga page over a paging channel meant for the hold state users. In oneembodiment, the mobile decodes the paging channel with some prearrangedperiodicity, to check for base station messages. On finding a pagemessage meant for it, it responds with an acknowledgement. In variousembodiments the acknowledgement is transmitted over a shared resource onthe uplink and is slaved to the page or grant message on the downlink.The mobile node 14 responds to a state change message by moving to theassigned state specified in the received state change message.

[0074] In one embodiment, when the mobile node 14 intends to migratefrom the hold state 410 to the on state 404, it transmits a statetransition request using its dedicated uplink communications channel,which is not shared with any other mobile nodes 16. Since the channel isnot shared, the base station 12 is able to receive the request withoutinterference and promptly grant the request assuming the requiredresources are available taking into account the priority of the userand/or the applications that the user may be using. The mobile onreceiving a grant message meant for it, responds with anacknowledgement. The acknowledgment is transmitted over a sharedresource on the uplink and is slaved to the grant message on thedownlink.

[0075] In one exemplary embodiment, when the mobile node does not intendto migrate to another state from the hold state, the mobile node may nottransmit any signal in its dedicated uplink communication resource,though the dedicated resource has been assigned to the mobile node andtherefore will not be used by any other mobile nodes. In this case, themobile node can temporarily shut down the transmission module andrelated functions thereby conserving power.

[0076] In another embodiment, the mobile node uses an on/off signalingin its dedicated uplink communication resource, where the mobile nodesends a fixed signal (on) when it intends to migrate to another state ordoes not send any signal (off) when it does not intend to migrate to anyother state. In this case, the transmission of the fixed signal can beinterpreted as a migration request to the on state if the transmissionoccurs at certain time instances and as a migration request to the sleepstate if the transmission occurs at some other time instances.

[0077] In order to provide reachability for a large number of mobilenodes 14, 16, the sleep state 408, requiring relatively fewcommunications resources, is also supported. The mobile node 14 cantransition into the sleep state 408, e.g., in response to user input, aperiod of inactivity, or a signal from the base station 12, from any ofthe other supported states 404, 404, 410.

[0078] In the sleep state 408 the mobile node 14 may, at the behest ofthe base station 12, serving the cell 10 signal its presence in the cell10. However, little other signaling is supported during this state 408of operation. In the exemplary embodiment, during the sleep state 408,timing control signaling and power control signaling are not supported.In addition, the mobile node is not allocated a dedicated uplink formaking resource requests and is not allocated bandwidth for use intransmitting payload data, e.g., as part of a communications sessionwith another node 16 conducted through the base station 12.

[0079] Transitions from the sleep state 408 to another state 404, 410occur by passing through access state 402. A shared (contention based),as opposed to a dedicated uplink, communications channel is used tocontact the base station 12 to request resources necessary to transitionfrom the sleep state 408 to another state 402, 404, 410. Thesetransitions could be initiated by the base station on the paging channelor by the mobile nodes 14, 16. Since the communications channel used torequest resources to transition from the sleep state is shared, a mobilenode 14 may encounter delays before being able to successfully transmitthe resource request to the base station 12. This is due to possiblecollisions with similar requests from other mobile nodes. Such delaysare not encountered in regard to transitions from the hold state 410 tothe on state due to the use of a dedicated uplink resource for requestswhile in the hold state 410.

[0080] The access state 402 is a state through which a node 14 in thesleep state 408 can transition into one of the other supported states404, 410. The transition out of the sleep state is normally triggered,by an action by a user of the mobile node 14, e.g., an attempt totransmit data to another mobile node 16 or by the base station 12. Uponentering the access state 402, transmission power control and timingcontrol signaling has not yet been established. During access stateoperation, timing control signaling is established and, in variousembodiments, full or partial transmission power control signaling isestablished with mobile node transmission output power levels beingadjusted accordingly. A mobile node can transition from the access state402, back to the sleep state 408 or to either the on state 404 or thehold state 410. Transition to the sleep state 408 may occur, e.g., inresponse to a user canceling a transmission request or a base station 12denying the node the resources required to complete the transition tothe hold or on states 404, 410. Transition from the access state to theon state 404 or hold state 410 normally occurs once the mobile node 14has restored power and timing synchronization signaling with the basestation 12 and has been granted the communications resource or resourcesrequired to maintain the state into which the mobile node 14 istransitioning.

[0081] The establishment of the timing synchronization and transmissionpower control signaling, in the access state 402, can take some amountof time during which data transmission is delayed. Furthermore, as notedabove, delays may result form the use of a shared resources to requestthe transition which can produce contentions between mobile nodes whichtake time to resolve. In addition, because of the use of sharedresources in requesting a state transition, it is difficult toprioritize between different nodes requesting state transition.

[0082] In some embodiments, for an individual cell 10, the maximumnumber of mobile nodes 14, 16 that can be in the sleep state 408 at anygiven time is set to be greater than the maximum number of mobile nodes14, 16 that can be in the hold state 410 at given time. In addition, themaximum number of mobile nodes 14, 16 which can be in the hold state 410at any given time is set to be greater than the maximum number of nodesthat can be in the on state 404 at any given time.

[0083] By supporting a hold state in accordance with the presentinvention, in addition to a sleep state, such delays can be avoided fora number of mobile nodes 14, 16, as transition from the hold state 410to the on state 404 does not go through the access state, while thenumber of nodes which can be supported by a single base station 12 islarger than would be possible without the use of the reduced signalinghold state.

[0084] From a power standpoint it is desirable that the amount of timeand thus power a mobile node spends monitoring for control signals beminimized. In order to minimize the amount of time and power a mobilenode spends monitoring for control signals, at least some downlinkcontrol signaling, i.e., signaling from the base station to one or moremobile nodes, is performed using multiple control channels. In oneembodiment of the invention, particularly well suited for use withmobile nodes capable of supporting multiple states of operation, aplurality of control channels are provided for communicating controlsignals from the base station to the mobile nodes. Each of the pluralityof common control channels is divided into a number of segments, e.g.,time slots, where each segment is dedicated, e.g., assigned, for use byone or a group of mobile nodes. In this case, a group of mobile nodesmay be, e.g., a subset of the mobile nodes in the system whichcorrespond to a multicast message group. In such an embodiment, thecontrol channels are common to multiple nodes, but each segment of achannel is dedicated, e.g., corresponds to, a particular one of themobile nodes or group of mobile nodes with other mobile nodes beingexcluded from using the dedicated segments. The dedicated segments of acommon control channel corresponding to an individual mobile noderepresent a dedicated control channel allocated to the individual mobilenode.

[0085] The pattern of control channel segment allocation is made knownto the individual mobile nodes 14, 16 in a cell, e.g., based oninformation transmitted to each particular node 14, 16 from the basestation 12.

[0086] To provide particularly efficient control channel signaling, basestation to mobile node control signaling may be performed at severaldifferent rates, with a different control channel being used for each ofthe different control channel signaling rates.

[0087] In order to minimize the amount of power and resources consumedby the task of monitoring control channels for information relevant to amobile node, each mobile node need only monitor to detect signals incontrol channel segments assigned to the particular node. This allowsthe mobile nodes to schedule control channel monitoring operations sothat the control channels need not be monitored on a continuous basiswhile still allowing the mobile nodes to receive control signals in atimely manner.

[0088] In one embodiment which is particularly well suited for use wheremobile nodes that support at least an on state, a hold state and a sleepstate, three different segmented control channels are used. The threecontrol channels include an assignment control channel, a fast pagingcontrol channel, and a slow paging control channel.

[0089] The fast paging control channel and slow paging control channelare periodic in nature, e.g., control signals are not transmitted interms of time on a continuous basis in these channels. Thus, mobilenodes need not spend power and resources monitoring these channels on acontinuous basis. In some embodiments, to further reduce the amount oftime and power a mobile needs to spend monitoring the fast and slowpaging channels, the channels are segmented and the segments arededicated to particular mobile nodes or groups of mobile nodes.

[0090] In order to minimize the amount of power and resources consumedby the task of monitoring control channels for information relevant to amobile node, each mobile node need only monitor to detect signals in thefast and slow paging control channel segments assigned to the particularnode. This allows the mobile nodes to schedule control channelmonitoring operations so that the control channels can be monitored on aless frequent basis than would be possible if all segments need to bemonitored for control signals.

[0091]FIG. 6 illustrates control signals 602, 620, 630 corresponding toexemplary assignment, fast paging and slow paging downlink controlchannels respectively. The fast paging control channel signal 602 isdivided into a plurality of segments, e.g., 1 ms time slots.Transmission in the assignment channel occurs, in the FIG. 6 embodiment,on a continuous basis. For each time slot, there is a correspondingtraffic channel segment or segments. Traffic channel segments areallocated by the base station 12 to mobile nodes 14, 16 by transmittinga mobile node identifier or mobile node group identifier in a time slotto indicate that the corresponding traffic segment or segments have beenassigned for use to the mobile node(s) corresponding to the transmittedidentifier. While in the on state mobile nodes 14, 16 monitor theassignment channel on a continuous basis, e.g., at a rate sufficient todetect the identifier included in each segment of the control channelused for traffic assignment purposes.

[0092] During the on state, in addition to the assignment channel eachmobile node 14, 16 monitors the periodic fast paging and slow pagingchannels.

[0093] In FIG. 6, fast paging signal 620 can be seen to be periodic innature. Each exemplary fast paging signal period 622, 626, 230, 634 is10 ms in duration. However, of this 10 ms period, the fast paging signalis actually transmitted for only a fraction of the full period, e.g., 2ms. The periods 623, 627, 631, 635 in which the fast paging signal istransmitted are segmented into time slots. The remaining portions 624,628, 632, 636 represent portions of time in which the fast pagingcontrol signal is not broadcast by the base station 12. While only two 1ms segments are shown in each fast paging on period 623, 627, 631, 635it is to be understood that there are normally several segments per onperiod.

[0094] To reduce the amount of time mobile nodes 14, 16 need monitor forfast paging control signals, fast paging control channel segments are,in some embodiments, dedicated to individual mobile nodes or groups ofmobile nodes. The information on which segments are dedicated to whichmobile nodes is normally conveyed to the mobile nodes 14, 16, e.g., formthe base station 12. Once the dedication information is known, themobile nodes 14, 16 can limit their monitoring of fast paging channelsegments to segments which are dedicated to them. In such embodiments,mobile nodes can monitor the fast paging channel at periodic intervalsgreater than the fast paging period without risking missing controlinformation transmitted to the mobile on the fast paging channel.

[0095] The segments of the fast paging channel are used to conveyinformation, e.g., commands, used to control the mobile node totransition between states. The segments of the fast paging channel canalso be used to instruct the mobile node to monitor the assignmentchannel, e.g., when the mobile node is in a state which has caused it tostop monitoring the assignment channel. Since the mobile nodes of thesystem know which segments of the fast paging channel are assigned tothem, commands may be included in the fast paging channel segmentswithout mobile node identifiers making for an efficient transmissionscheme.

[0096] The slow paging channel is segmented and used to conveyinformation in the same manner as the fast paging channel. Theinformation conveyed using the slow paging channel may be the same as,or similar to, the information and commands that are transmitted usingthe fast paging channel.

[0097] In FIG. 6, signal 630 represents an exemplary slow paging channelsignal. Note that the full slow paging signal period 632 is longer thanthe paging period 622 of the fast paging channel. Reference numbers 631and 634 are used in FIG. 6 to show portions of a slow paging period.Given that the slow paging period is longer than the fast paging period,the time between control signal transmission in the slow paging channeltends to be greater than in the fast paging channel. This means that themobile node may discontinue monitoring the slow paging channel forlonger intervals than is possible with the fast paging channel. It alsoimplies, however, that it may take, on average, longer for a controlsignal transmitted on the slow paging channel to be received by theintended mobile node.

[0098] In FIG. 6, two slow paging signal transmission on signal periods640, 642 are shown. Signal periods 639, 641, 643 correspond to slowpaging channel signal periods during which no slow paging signal istransmitted.

[0099] Since the fast and slow paging channels are period in nature, ifthe transmission on periods are staggered so that they do not overlap,the fast and slow paging channels may be implemented using the samephysical transmission resources, e.g., tones, with the tones beinginterpreted as corresponding to either the fast or slow paging channeldepending on the time period to which the tones correspond.

[0100] The spacing between segments allocated to a particular mobilenode in the slow paging channel are often, but need not be, greater thanin the fast paging channel. This generally means, in terms of time, thata mobile device needs to monitor the slow paging channel at intervalswhich are more widely spaced than the intervals at which the fast pagingchannel is monitored. As a result of the greater spacing of the segmentsin the slow paging channel, power required to monitor this channel isnormally less than that required to monitor the fast paging channel.

[0101] In accordance with one embodiment of the present inventiondifferent numbers of downlink control channels are monitored indifferent states. In such embodiments, the assignment, fast paging andslow paging channels are not monitored in all states. Rather, in the onstate the greatest number of downlink control channels are monitored,fewer downlink control channels are monitored in the hold state and thelowest number of downlink control channels are monitored in the sleepstate.

[0102]FIG. 7 shows a table 700 which illustrates the three exemplarybase station to mobile node (downlink) control signaling channels andthe corresponding four exemplary mobile node states of operationdiscussed above. In the table 700, a check is used to show controlchannels which are monitored for a given state while an X is used toindicate a control channel which is not monitored. A dashed check isused to show a control channel which may not be monitored during aportion of the time in that state but is monitored for at least aportion of the time in the state.

[0103] From FIG. 7 the first row 702 corresponds to the on state, thesecond row 704 corresponds to the access state, the third row 706corresponds to the hold state and the fourth row 708 corresponds to thesleep state. Columns in the table 700 correspond to different segmentedcontrol channels. The first column 710 corresponds to the assignmentchannel, the second column 712 corresponds to the fast paging channel,while the third column 714 corresponds to the slow paging channel.

[0104] As can be seen from the table 700, while in the on state a mobilenode 14, 16 monitors the assignment channel, fast paging control channeland slow paging control channel.

[0105] For a portion of the access state, which represents a transitionbetween the on state and either the hold state or the sleep state, theassignment and fast paging channels are monitored. The slow pagingchannel is monitored for the full period of time the mobile node remainsin the access state. As discussed above, monitoring of the fast pagingand slow paging channels requires a mobile node to be actively engagedin monitoring on a periodic, as opposed to a continuous, basis.

[0106] While in the hold state, the assignment channel is not monitored.However, the fast paging channel and slow paging channel are monitored.Accordingly, a mobile node in the hold state can be instructed to changestates and/or monitor the assignment channel for traffic channel segmentassignment information in a relatively short period of time.

[0107] In the sleep state, of the three control channels shown in FIG.6, only the slow paging channel is monitored by the mobile node.Accordingly, a mobile node 14, 16 in the hold state can be instructed tochange states and/or monitor the assignment channel for traffic channelsegment assignment information but such instructions may take longer tobe detected, on average, than when in the hold state.

[0108] By decreasing the number of control channels that are monitoredas operation proceeds from the on state to the less active sleep state,mobile node monitoring and processing resources, and thus powerconsumption, can be effectively controlled. Thus, the sleep staterequires less mobile node resources, including power, than the holdstate. Similarly, the hold state requires less mobile node resources,including power, than the on state.

[0109] Mobile node transitions from active to less active states ofoperation may occur in response to commands to change states receivedfrom a base station. However, in various embodiments of the inventionsuch transitions are also initiated by mobile nodes 14, 16 in responseto detecting periods of downlink control signal inactivity or reducedactivity pertaining to the mobile node.

[0110] In one embodiment of the invention, activity relating to a mobilenode 14, 16 on the control channel which will cease to be monitored ifthe mobile node reduces its state of activity by one level is used todetermine when the mobile node should, on its own, switch to the loweractivity level state of operation. For example, in the case of the onstate, a mobile node monitors the assignment channel for signalsdirected to it. When failing to detect signals on the assignment channelfor a preselected period of time, or a reduced message level for aperiod of time, the mobile node 14, 16 switches from the on state to thehold state and ceases to monitor the assignment channel.

[0111] While in the hold state, the mobile node 14, 16 monitors the fastpaging channel for activity to determine, among other things, if itshould switch to a lower activity state of operation, e.g., the sleepstate. When failing to detect signals for a preselected period of time,or a reduced signal level for a period of time, the mobile node 14, 16switches from the bold state to the sleep state and ceases to monitorthe fast paging channel.

[0112] Using the above discussed methods, monitoring, signal processingand power resources can be conserved in a mobile node 14, 16 through theuse of multiple states of operation and through the use of multiplesegmented control channels. In addition, limited control resources,e.g., bandwidth used for communicating control information from a basestation to a mobile node, is used efficiently as a result of usingmultiple control channels, e.g., segmented control channels of the typedescribed above.

[0113] Numerous variations on the above described methods and apparatuswill be apparent to one of ordinary skill in the art in view of theabove description of the invention. Such variations remain within thescope of the invention.

What is claimed is:
 1. A communications method, the method comprising:operating a first wireless terminal, at different times, in each one ofthree different operational states, the three different operationalstates including a first state, a second state and a third state,wherein operating the first wireless terminal in the first stateincludes using a first amount of a control communications resource tocommunicate control information between said first wireless terminal anda base station; wherein operating the first wireless terminal in thesecond state includes using a second amount of the controlcommunications resource to communicate control information between saidfirst wireless terminal and the base station, the second amount ofcontrol communications resource being less than the first amount; andwherein operating the first wireless terminal in the third stateincludes using less of the control communications resource than is usedby the first wireless terminal in either of the first or second states.2. The communications method of claim 1, wherein operating the firstwireless terminal in the first state to use a first amount of a controlcommunications resource includes: operating the first wireless terminalto perform power control signaling operations and timing controlsignaling operations.
 3. The method of claim 2, further comprising:operating the first wireless terminal to transition from the first stateto the second state, said transitioning including reducing the rate ofpower control signaling operations performed by said first wirelessterminal.
 4. The method of claim 3, further comprising: operating thefirst wireless terminal to transition from said second state to thethird state, the step of transitioning from said second state to saidthird state including ceasing to perform transmission timing controlupdates.
 5. The method of claim 3, wherein reducing the rate of powercontrol signaling includes ceasing to monitor for power control signalsfrom the base station.
 6. The method of claim 3, wherein reducing therate of power control signaling operations includes performingtransmission power control update operations at a greater interval thantransmission power control update operations were performed in saidfirst state.
 7. The method of claim 6, wherein transitioning from thesecond state to the third state includes operating the first wirelessterminal to cease performing transmission power control updateoperations.
 8. The method of claim 2, further comprising the step of:operating the first wireless terminal to transition from said thirdstate to one of said first and said second states, the step oftransitioning to one of said first and second states including resumingtransmission timing control update operations.
 9. The method of claim 8,wherein operating the first wireless terminal to transition from saidthird state to one of said first state and said second state includesoperating the first wireless terminal to resume transmission powercontrol signaling operations.
 10. The method of claim 9, whereinoperating the first wireless terminal to resume transmission timingcontrol signaling includes: transmitting a request to the base stationfor the allocation of communications resources required to performtransmission timing control signaling.
 11. The method of claim 10,wherein transmitting a request for communications resources required toperform transmission timing control signaling includes: transmittingsaid request using a shared segment of a communications channel.
 12. Themethod of claim 11, further comprising: operating the first wirelessterminal to transition from said second state to said first state, thestep of transitioning from said second state to said first stateincluding transmitting a request for a dedicated communications resourcethat can be used to transmit data to be communicated to said basestation.
 13. The method of claim 9, wherein operating the first wirelessterminal to transmit a request for a dedicated communications resourcethat can be used to transmit data includes transmitting the resourcerequest to a base station using a dedicated resource request uplinkassigned to the first wireless terminal.
 14. The method of claim 1,wherein said control communications resource is control signalingbandwidth used for communicating control signals between said basestation and a plurality of wireless terminals served by said basestation.
 15. The method of claim 14, wherein said first state is an onstate, said second state is a hold state, and said third state is asleep state, the method further comprising: operating the first wirelessterminal to transmit and receive data as part of a communicationssession with another terminal during at least a portion of said onstate.
 16. The method of claim 15, further comprising: operating thefirst wireless terminal to receive data from another terminal during atleast a portion of said hold state without transmitting data at any timewhile operating in said hold state.
 17. The method of claim 16, whereinoperating said first wireless terminal in said sleep state includescontrolling said wireless terminal so that data corresponding to acommunications session is neither transmitted from said first wirelessterminal or received by said first wireless terminal during any portionof said sleep state.
 18. The method of claim 1, wherein said first stateis an on state, said second state is a hold state, and said third stateis a sleep state, the method further comprising: operating a secondwireless terminal, at different times, in each one of said on state,said hold state and said sleep state; wherein operating the secondwireless terminal in the on state includes using a fourth amount ofcontrol communications bandwidth to communicate control informationbetween said second wireless terminal and said base station; and whereinoperating the second wireless terminal in the hold state includes usinga fifth amount of the control communications bandwidth to communicatecontrol information between said second wireless terminal and the basestation, the fifth amount of control communications bandwidth being lessthan the first amount.
 19. The method of claim 18, further comprisingoperating the second wireless terminal to transmit and receive data aspart of a communications session with another terminal during at least aportion of time during which said second terminal is operated in said onstate.
 20. The method of claim 19, further comprising: operating thesecond wireless terminal to receive data from another terminal during atleast a portion of the time said second wireless terminal is operated insaid hold state without transmitting data at any time while operatingsaid second wireless terminal in said hold state.
 21. The method ofclaim 20, wherein operating said second wireless terminal in said sleepstate includes controlling said second wireless terminal so that datacorresponding to a communications session is neither transmitted fromsaid second wireless terminal or received by said second wirelessterminal during any portion of time said wireless terminal is operatedin said sleep state.
 22. The method of claim 19, wherein said data to betransmitted as part of a communications session includes IP packets atleast some of which include speech data; and wherein said secondwireless terminal transmits said IP packets to said base station usingorthogonal frequency division multiplexed signals.
 23. A mobilecommunications device including: control means used to control themobile communications device to: i) operate in an on state in which themobile communications device uses a first amount of control signalingresources for the communication of control information between saidmobile communications device and a base station; ii) transition themobile communications device from the on state to a hold state in whichthe first mobile communications device uses less control signalingresources for the communication of control information between saidmobile device and a base station than is used by the mobilecommunications device in the on state; and iii) transition the mobilecommunications device from said hold-state to a sleep state in which themobile communications device uses less control signaling resources thanthe mobile communications device uses in said hold state.
 24. The mobilecommunications device of claim 23, wherein said control means controlsthe mobile communications device to perform transmission timing controlsignaling operations, transmission power control signaling operations,and transmit data, during said on state.
 25. The mobile communicationsdevice of claim 24, wherein said control means controls the mobilecommunications device, as part of transitioning from said on-state tosaid hold state, to reduce the rate of power control signalingoperations performed by said first mobile communications device.
 26. Themobile communications device of claim 25, wherein said control meanscontrols the mobile communications device, as part of transitioning fromsaid hold-state to said sleep-state, to cease performing transmissiontiming control update operations.
 27. The mobile communications deviceof claim 25, further comprising: means for controlling the mobilecommunications device to transition from said sleep-state to one of saidon-state and said hold-state, wherein transitioning to one of saidon-state and said hold-state includes resuming transmission timingcontrol update operations.
 28. The mobile communications device of claim27, further comprising: means for controlling the mobile communicationsdevice to transition from said hold-state to said on-state, whereintransitioning from said hold-state to said-on state includestransmitting a request for a dedicated communications resource that canbe used to transmit data to be communicated to said base station.
 29. Acommunications system comprising: a base station, said base stationcontrolling the allocation of control signaling resources and datatransmission resources to a plurality of mobile nodes serviced by saidbase station, said base station controlling a first subset of saidplurality of mobile nodes to operate in an on state wherein nodes insaid first subset are allocated data communication resources to transmitdata and control signaling resources to perform a first level of controlsignaling, said base station further controlling a second subset of saidplurality of mobile nodes to operate in an hold state wherein nodes insaid second subset are allocated control signaling resources to performa second level of control signaling which is less than said first levelof control signaling; and said base station further controlling a thirdsubset of said plurality of mobile nodes to operate in a sleep statewherein nodes in said third subset are allocated less control signalingresources than mobile nodes in either said first subset or said secondsubset.
 30. The communications system of claim 29, wherein the systemincludes said plurality of mobile nodes, the first subset of mobilenodes includes means for performing transmission timing controlsignaling operations and transmission power control signaling operationswhile in said on state.
 31. The communications system of claim 30,wherein the second subset of mobile nodes includes means for performingtransmission timing control signaling operations and reduced ratetransmission power control signaling operations while in said holdstate.
 32. The communications system of claim 30, wherein said secondsubset of mobile nodes includes means for reducing the rate oftransmission power control signaling operations as part of transitioningfrom said on state to said hold state.
 33. The communication system ofclaim 32, wherein said second set of mobile nodes includes means forhalting transmission power control update operations when transitioninginto said hold state from said on state.
 34. The communication system ofclaim 32, wherein said third subset of mobile nodes includes means forterminating the transmission of timing control signals whentransitioning into said sleep state from said hold state.
 35. The systemof claim 29, further comprising said plurality of mobile nodes, thethird subset of mobile nodes including more communications devices thansaid second subset of mobile nodes.
 36. The system of claim 35, whereinthe second subset of mobile nodes includes more nodes than said firstsubset of mobile nodes.
 37. The system of claim 36, wherein said thirdsubset of mobile nodes do not perform transmission power controlsignaling operations.
 38. The system of claim 37, wherein said secondsubset of mobile nodes do not perform transmission power controlsignaling operations.
 39. The system of claim 37, wherein said secondsubset of mobile nodes perform power control signaling operations at arate which is lower than the rate at which mobile nodes in said firstsubset perform transmission power control signaling operations.